Delay action fuse for projectiles and the like



June 15, 1937. E. REMONDY DELAY ACTION FUSE FOR PROJECTILES AND THE LIKE Filed Dec. 4, 1935 Fatented June 15, 1937 ATENT OFFICE DELAY ACTION FUSE FOR PROJECTILES AND THE LIKE Lon Emile Rmondy, Paris, France 13 Claims.

As is well known, it is often necessary or desirable to delay for a predetermined time, but to then ensure the operation of the ignition or other mechanisms comprised by projectiles and bombs of the most diverse kinds, whether the said projectiles are intended to be thrown by a gun or dropped under the influence of gravity alone. Thus, numerous devices have been proposed for bringing about the operation of the fuses of projectiles at the end of a predetermined time, and time fuses have been devised wherein the delayed operation is effected by a combustion mechanism, as of the time type, or a clockwork mechanism.

Another problem which very frequently arises is to ensure the destruction of the mechanism or the harmlessness of a projectile or bomb when the latter, for some reason or other, has failed to burst at the end of its trajectory.

Finally, delay devices of various kinds are employed for ensuring the operation and destruction of a projectile employed as a trajectory tracer.

This invention relates to a combination of elements which is adapted for use in explosive shells,

5 as well as for tracer projectiles or for bombs, and enables the operation desired to be ensured at the end of a predetermined time without involving the use of special clockwork or other mechanisms, while reducing the use of fuse compositions to the minimum.

According to the invention, the combination of elements for obtaining these results comprises a member housed in the interior of the projectile and capable of producing and transmitting heat upon being ignited by the operation of a primary fuse device rendered active under the effect of the throwing or impact of the projectile, the heat producing and transmitting member being constructed so that, by its constitution or proporo tions, the rate of heat transmission varies according to the requirements or the special application considered. A third element of the combination is constituted by the device in which the heat transmitted is utilized to ensure an operation. This device may be one of the elements of a firing mechanism, striker or detonator, the heat transmitted then having the effect of ensuring at the end of a predetermined time the release of the striker or of the detonator for arming them or for the actual firing. In other words, the system according to the invention comprises the combination of a primary striker or percussive device (A) for creating a fiame in the interior of the projectile, an intermediate device (B) for producing and transmitting heat when ignited by the operation of the primary device (A), the heat production and transmission being effected at a variable rate according to the constitution or dimensions of the said device, and a third device (C) wherein the heat transmitted is finally utilized for ensuring an operation.

In the two forms of the invention described and illustrated in the accompanying drawing, the third device (C) of the fuse comprises an auxiliary igniting mechanism having a striker and a detonator cap, one of these two elements (for example, the detonator cap) being permanently fixed with respect to the body of the projectile or fuse, while the other (for example, the striker) is adapted to move toward the first element under the action of a spring but is temporarily maintained in a fixed position with respect to the fuse or projectile body by a locking or retaining member adapted to become inoperative under the action of the heat produced by the combustion of an appropriate composition constituting the intermediate device (B) which is ignited by the operation of the primary firing device (A). The movable element of the auxiliary igniting mechanism is disposed within a recess in the fuse or projectile body surrounded by a heat conducting wall the outer surface of which is in direct contact with the heat producing composition, the combustion heat of the latter being transmitted by conduction through the said wall to the looking or retaining member which, under the influence of the heat, is rendered inoperative and liberates the movable member so that the latter may be projected against the complementary element of the auxiliary igniting mechanism and produce a detonation which sets off the explosive charge of the projectile.

In the drawing, wherein two specific forms of fuse mechanism have been illustrated as exemplary of the invention:

Figure 1 is a sectional elevation of a portion of a fuse construction illustrating the application of the invention to the firing mechanism of an explosive shell wherein firing is to be effected a predetermined time after impact of the projectile with an obstacle; and

Figure '2 is a sectional elevation of another form of the invention as applied to the firing mechanism of an explosive shell wherein the operation of the auxiliary igniting mechanism which ignites the explosive charge of the projectile is effected in two stages.

In the embodiment of the invention shown in Figure 1, the projectile comprises a percussion fuse of any known type (not shown) which, as shown, will act as the primary firing system A intended by the ignition of its percussion cap to provide a name which will ignite the heat producing element 33 the heat from which is transmitted to and brings about the operation of the system C at the end of a predetermined time. As shown, the heat producing device is constituted by a ring of slow burning powder B, for which a suitable housing is provided in the body of the projectile or in a body carrying the primary percussion fuse A (not shown) If desired, the outer wall of the recess in which the'powder B is housed may be provided with a lining b of any suitable heat insulating material. The inner wall at of said recess through which is transmitted the heat producedby the powder B also forms the outer wall of a cavity 6 in the projectile or fuse body in which is housed the striker c of the operating fuse which by impact against the fixed detonator C is adapted to effect bursting of the charge of the projectile a predetermined time after percussion of primary fuse A. The striker c of the operating fuse is urged toward the fixed detonator C by the action of a spring 0 The striker is normally maintained in a fixed position, however, by a fusible joint f, or by any other fusible means adapted to become inoperative upon being heated, provided between the said striker c and the wall a of the cavity e. This wall thus comprises on its internal face the fusible joint 1 and is in contact by its external face with the internal wall of the powder ring B.

When the projectile strikes an obstacle, the front percussion fuse A (not shown) operates under the effect of the impact with the said obstacle, and the flame of the percussion cap is transmitted to the heat producing and transmitting device B-h. At the end of the desired time, the heat produced by the combustion of the powder B and transmitted through the wall a ensures the fusion of the joint and hence the release of the striker 0 which, under the action of the spring 0 is then projected against the detonator C.

The embodiment of the invention illustrated in Figure 2 also relates to a projectile intended, like that of the example in Figure 1, to be able to burst only after the elapse of a certain time after impact between it and the objective or any obstacle. In this example, however, the arrangement is such that the heat producing and transmitting sys tem brings about only the arming of the device 0, final operation thereof being produced only under the effect of a second impact between the projectile and an obstacle or under the effect of a violent vibration in the vicinity of the projectile.

As shown by the figure, the primary firing device A is in this case constituted by a percussion fuse of a known type having its flame transmitting passage 9 terminating at the upper face of a mass 13 of slow burning powder of cylindrical or any other appropriate form housed in a recess of corresponding form in the body of the projectile, said recess being provided with an insulating lining b, if desired. The heat produced by the powder B is transmitted through a separating wall a to a fusible joint 1 interposed between the wall and a striker support 0 subjected to the action of a spring 0 The fusion of the fusible joint 1 merely causes the release of the striker which is then armed but which remains at a distance from the detonator C by reason of its being supported on a shoulder h provided on the inner surface of the wall a of its housing. This shoulder may be provided on only a portion of the cross section of the housing, and the release of the striker upon encountering a fresh obstacle or under the effect of any other impact or vibration of the surroundings may be facilitated by an unbalancing of the said striker, as by providing the strik-.;r with a small mass 0 located opposite shoulder and producing a bias tending to dislodge the striker from said shoulder.

Although only two different forms of the invention have been described and illustrated in the accompanying drawing, it will be obvious that the invention is not limited to the specific structures disclosed but is capable of a variety of me chanical embodiments. Various changes, which will now suggest themselves to those skilled in the art, may be made in the form, details of con-- struction and arrangement of the parts without departing from the spirit of the nvention, Reference is therefore to be had to the appended claims for a definition of the limits of the invention.

What is claimed is:-

1. In a delay action fuse mechan sm for a projectile containing a bursting charge, the combination of a priniary firing means for initiating the explosion of the bursting charge, a charge of heat producing material adapted to be ignited by said primary firing means, an auxiliary firing mechanism for exploding said bursting charge, means normally retaining said auxiliary firing mechanism in inoperative position but so constructed and arranged as to render the latter operable upon being heated, and a heat transmitting wall separating said heat producing material from said auxiliary firing mechanism and retaining means, said wall being so constructed and arranged that heat sufficient to ensure the operation of said auxiliary firing mechanism is transmitted therethrough from said heat producing material to said retaining means at a rate which establishes the delay in the operation of the fuse mechanism.

2. In a delay action fuse mechanism for a projectile containing a bursting charge, the combination of a primary firing means for initiating the explosion of the bursting charge, a charge of slow burning powder adapted to be ignited by said primary firing means, an auxiliary firing mechanism for exploding said bursting charge, means normally retaining said auxiliary firing mechanism in inoperative position but so constructed and arranged as to render the latter operable upon being heated, and a heat transmitting wall separating sa d charge of slow burning powder from said auxiliary firing mechanism and retaining means through which the heat of combustion of said powder is transmitted to said retaining means at such a rate as, and in sufficient amount, to ensure operation of said auxiliary firing mechanism a predetermined time after operation of said primary firing means.

3. In a delay action fuse mechanism for a projectile containing a bursting charge, the combination of a primary firing means for initiating the explosion of the bur -ing charge, a sheath of slow burning powder adapted to be ignited by said primary firing means, an auxiliary firing mechanism for exploding said bursting charge surrounded by said sheath and including a fixed and a movable element, means normally retaining said movable element in a fixed position out of contact with the associated fixed element but so constructed and arranged as to release aid movable element upon being heated, and a heat transmitting wall separating said sheath of slow burning powder from said auxiliary firing mechanism and retaining means through which the heat of combustion of said powder is transmitted to said retaining means at such a rate as, and in sufficient amount, to ensure release of the movable element of said auxiliary firing mechanism a predetermined time after operation of said primary firing means.

4. In a delay action fuse mechanism for a projectile containing a bursting charge, the combination of a fuse body, a primary firing means carriedby said fuse body for initiating the explosion of the bursting charge, a charge of heat producing material adapted to be ignited by said primary firing means, a chamber formed in said fuse body to receive said charge of heat producing material, an auxiliary firing mechanism for exploding said bursting charge housed within said fuse body, means normally retaining said auxiliary firing mechanism in inoperative position but so constructed and arranged as to render the latter operable upon being heated, a wall separating said charge of heat producing material from said auxiliary firing mechanism and retaining means through which the heat of combustio-n of said material is transmitted to said retaining means at such a rate as, and in suificient amount, to render said auxiliary firing mechanism operable a predetermined time after operation of said primary firing means, and insulating means for minimizing the transmission of said combustion heat through parts of said fuse body other than said wall between the charge of heat producing material and the auxiliary firing mechanism.

5. A delay action fuse mechanism according to claim 4 wherein the charge of heat producing material surrounds at least a portion of the auxiliary firing mechanism with its inner surface in contact with said heat transmitting wall and wherein the insulating means comprises a layer of heat insulating material interposed between the outer surface of said charge and the fuse body.

6. In a delay action fuse mechanism for a projectile containing a bursting charge, the combination of a primary firing mechanism for initiating the explosion of the bursting charge, a charge of combustible material adapted to be ignited by said primary firing mechanism, an auxiliary firing mechanism for exploding said bursting charge including striker and detonator elements and a spring, one of said elements being permanently fixed with respect to the projectile body and the other being movable into firing contact with the first under the action of said spring, and means normally retaining said movable element in a fixed inoperable position, said means being so constructed and arranged as to release said movable element when heated by combustion of said combustible material.

7. In a delay action fuse mechanism for a projectile containing a bursting charge, the combination of a primary firing mechanism for initiating the explosion of the bursting charge, a charge of combustible material adapted to be ignited by said primary firing mechanism, an auxiliary firing mechanism for exploding said bursting charge including striker and detonator elements and a spring, one of said elements being permanently fixed with respect to the projectile body and the other being movable into firing contact with the first under the action of said spring, a housing for said auxiliary firing mechanism having a heat transmitting Wall adjacent said movable element and in direct contact with said charge of combustible material, and means normally retaining said movable element in a fixed inoperable position within said housing,

said means being so constructed and arranged.

as to release said movable element upon the transmission thereto through said wall of the heat of combustion of said combustible material.

8. In a delay action fuse mechanism for a projectile containing a bursting charge, the combination of a primary firing mechanism for initiating the explosion of the bursting charge, a charge of combustible material adapted to be ignited by said primary firing mechanism, an auxiliary firing mechanism for exploding said bursting charge including striker and detonator elements and a spring, one of said elements being permanently fixed with respect to the projectile body and the other being movable into firing contact with the first under the action of said spring, means normally retaining said movable element in a fixed inoperable position, said means being so constructed and arranged as to release said movable element when heated by combustion of said combustible material, and additional means for holding said movable element in inoperative position so constructed and arranged as to release said element only in response to an impact or vibration of the projectile occurring after said element has been released by said retaining means.

9. A delay action fuse mechanism according to claim '7 wherein said retaining means consists of a fusible joint interposed between the movable element of said auxiliary firing mechanism and the heat transmitting wall of said housing.

10. A delay action fuse mechanism according to claim 7 including a shoulder formed within said housing upon which the movable element of said auxiliary firing mechanism rests and from which said element is dislodged only in response to an impact or vibration of the projectile occurring after said element has been released by said retaining means.

11. In a delay action fuse mechanism for a projectile containing a bursting charge, the combination of firing means for initiating the explosion of the bursting charge, a charge of slow burning powder adapted to be ignited by said firing means, a detonating device for exploding said bursting charge including a movable percussive element, a housing for said detonating device, and fusible means normally retaining said movable percussive element in a fixed position relative to said housing, said charge of slow burning powder and fusible means being so positioned with respect to the wall of said housing that the heat of combustion of said powder is transmitted through said wall to said fusible means, fuses the latter, and thereby releases said percussive element from said casing a predetermined time after operation of said firing means.

12. In a delay action fuse mechanism for a projectile containing a bursting charge, the combination of firing means for initiating the explosion of the bursting charge, a charge of slow burning powder adapted to be ignited by said firing means, a detonating device for exploding said bursting charge including a movable percussive element, a wall of heat transmitting material surrounding said detonating device, and fusible means normally retaining said movable percussive element in a fixed position relative to said wall, said charge of slow burning powder being in contact with said wall opposite said fusible means whereby the heat of combustion of said powder is transmitted through said wall to said fusible means, fuses the latter, and there- 10 by releases said percussive element from said Wall a predetermined time after operation of said firing means.

13. A fuse mechanism according to claim 11 including additional means for holding said percussive element in inoperative position so constructed and arranged as to release said element only in response to an impact or vibration of the projectile occurring after fusion of said fusible means. 

